USB powered laptop speakers: Question

Discussion in 'Computer Support' started by me@privacy.net, Aug 26, 2010.

  1. Guest

    This may be a dumb question but do USB powered laptop
    speaker not only get their power via the USB connection
    but the sound SIGNAL as well?

    Or must you still have a cable the connects the
    speakers to the laptops speaker connection as well?
     
    , Aug 26, 2010
    #1
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  2. Tony Guest

    Have you ever used USB speakers? One cable links the two speakers and they
    power up from the USB port.

    chuckcar wrote:

    > wrote in news::
    >
    > > This may be a dumb question but do USB powered laptop
    > > speaker not only get their power via the USB connection
    > > but the sound SIGNAL as well?
    > >
    > > Or must you still have a cable the connects the
    > > speakers to the laptops speaker connection as well?
    > >

    > Do they come with an adapter? surely that's not hard to find out?
    >
    > --
    > (setq (chuck nil) car(chuck) )


    --
    The Grandmaster of the CyberFROG

    Come get your ticket to CyberFROG city

    Nay, Art thou decideth playeth ye simpleton games. *Some* of us know proper
    manners

    Very few. I used to take calls from *rank* noobs but got fired the first day
    on the job for potty mouth,

    Hamster isn't a newsreader it's a mistake!

    El-Gonzo Jackson FROGS both me and Chuckcar

    Master Juba was a black man imitating a white man imitating a black man

    Using my technical prowess and computer abilities to answer questions beyond
    the realm of understandability

    Regards Tony... Making usenet better for everyone everyday
     
    Tony, Aug 26, 2010
    #2
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  3. Tony Guest

    By the way Chuck you computer clock is about a minute and a half fast.

    chuckcar wrote:

    > wrote in news::
    >
    > > This may be a dumb question but do USB powered laptop
    > > speaker not only get their power via the USB connection
    > > but the sound SIGNAL as well?
    > >
    > > Or must you still have a cable the connects the
    > > speakers to the laptops speaker connection as well?
    > >

    > Do they come with an adapter? surely that's not hard to find out?
    >
    > --
    > (setq (chuck nil) car(chuck) )


    --
    The Grandmaster of the CyberFROG

    Come get your ticket to CyberFROG city

    Nay, Art thou decideth playeth ye simpleton games. *Some* of us know proper
    manners

    Very few. I used to take calls from *rank* noobs but got fired the first day
    on the job for potty mouth,

    Hamster isn't a newsreader it's a mistake!

    El-Gonzo Jackson FROGS both me and Chuckcar

    Master Juba was a black man imitating a white man imitating a black man

    Using my technical prowess and computer abilities to answer questions beyond
    the realm of understandability

    Regards Tony... Making usenet better for everyone everyday
     
    Tony, Aug 26, 2010
    #3
  4. chuckcar Guest

    wrote in news::

    > This may be a dumb question but do USB powered laptop
    > speaker not only get their power via the USB connection
    > but the sound SIGNAL as well?
    >
    > Or must you still have a cable the connects the
    > speakers to the laptops speaker connection as well?
    >

    Do they come with an adapter? surely that's not hard to find out?


    --
    (setq (chuck nil) car(chuck) )
     
    chuckcar, Aug 26, 2010
    #4
  5. Meat Plow Guest

    On Thu, 26 Aug 2010 11:01:09 -0500, me wrote:

    > This may be a dumb question but do USB powered laptop speaker not only
    > get their power via the USB connection but the sound SIGNAL as well?
    >
    > Or must you still have a cable the connects the speakers to the laptops
    > speaker connection as well?


    The one USB speaker I have any experience with appears as a USB sound
    device. Why not hit google.com up and do a little research? I would bet
    they are made to merely power off the USB 5 volts or service as an
    external USB powered sound device.



    --
    Live Fast, Die Young and Leave a Pretty Corpse
     
    Meat Plow, Aug 26, 2010
    #5
  6. Desk Rabbit Guest

    On 26/08/2010 17:01, wrote:
    > This may be a dumb question but do USB powered laptop
    > speaker not only get their power via the USB connection
    > but the sound SIGNAL as well?

    I doubt there's much power in the signal (which will be a digital stream
    anyway) but there is a 5volt power available from the USB port which
    should be enough to power a small amplifier.


    > Or must you still have a cable the connects the
    > speakers to the laptops speaker connection as well?

    Try Google with the phrase - how do usb speakers work
     
    Desk Rabbit, Aug 26, 2010
    #6
  7. ian field Guest

    "Desk Rabbit" <> wrote in message
    news:i564ks$klr$...
    > On 26/08/2010 17:01, wrote:
    >> This may be a dumb question but do USB powered laptop
    >> speaker not only get their power via the USB connection
    >> but the sound SIGNAL as well?

    > I doubt there's much power in the signal (which will be a digital stream
    > anyway) but there is a 5volt power available from the USB port which
    > should be enough to power a small amplifier.


    A BTL amplifier can produce pretty impressive output for only 5V supply.
     
    ian field, Aug 26, 2010
    #7
  8. Desk Rabbit Guest

    On 26/08/2010 17:51, ian field wrote:
    > "Desk Rabbit"<> wrote in message
    > news:i564ks$klr$...
    >> On 26/08/2010 17:01, wrote:
    >>> This may be a dumb question but do USB powered laptop
    >>> speaker not only get their power via the USB connection
    >>> but the sound SIGNAL as well?

    >> I doubt there's much power in the signal (which will be a digital stream
    >> anyway) but there is a 5volt power available from the USB port which
    >> should be enough to power a small amplifier.

    >
    > A BTL amplifier can produce pretty impressive output for only 5V supply.


    I'm sure it can but bear in mind that most USB ports can only deliver 5v
    @ 500ma which is not a lot to play with. Your values of impressive must
    be considerably lower than mine - I do get to play with 3Kw+ PA systems
    occasionally though, now that is an impressive output ;-)
     
    Desk Rabbit, Aug 26, 2010
    #8
  9. ian field Guest

    "Desk Rabbit" <> wrote in message
    news:i568q4$3ct$...
    > On 26/08/2010 17:51, ian field wrote:
    >> "Desk Rabbit"<> wrote in message
    >> news:i564ks$klr$...
    >>> On 26/08/2010 17:01, wrote:
    >>>> This may be a dumb question but do USB powered laptop
    >>>> speaker not only get their power via the USB connection
    >>>> but the sound SIGNAL as well?
    >>> I doubt there's much power in the signal (which will be a digital stream
    >>> anyway) but there is a 5volt power available from the USB port which
    >>> should be enough to power a small amplifier.

    >>
    >> A BTL amplifier can produce pretty impressive output for only 5V supply.

    >
    > I'm sure it can but bear in mind that most USB ports can only deliver 5v @
    > 500ma which is not a lot to play with. Your values of impressive must be
    > considerably lower than mine - I do get to play with 3Kw+ PA systems
    > occasionally though, now that is an impressive output ;-)
    >


    Did you somehow miss the bit where I said "for a 5V supply"?
     
    ian field, Aug 26, 2010
    #9
  10. Meat Plow Guest

    On Thu, 26 Aug 2010 18:38:12 +0100, Desk Rabbit wrote:

    > On 26/08/2010 17:51, ian field wrote:
    >> "Desk Rabbit"<> wrote in message
    >> news:i564ks$klr$...
    >>> On 26/08/2010 17:01, wrote:
    >>>> This may be a dumb question but do USB powered laptop speaker not
    >>>> only get their power via the USB connection but the sound SIGNAL as
    >>>> well?
    >>> I doubt there's much power in the signal (which will be a digital
    >>> stream anyway) but there is a 5volt power available from the USB port
    >>> which should be enough to power a small amplifier.

    >>
    >> A BTL amplifier can produce pretty impressive output for only 5V
    >> supply.

    >
    > I'm sure it can but bear in mind that most USB ports can only deliver 5v
    > @ 500ma which is not a lot to play with. Your values of impressive must
    > be considerably lower than mine - I do get to play with 3Kw+ PA systems
    > occasionally though, now that is an impressive output ;-)


    My bass guitar rig is a 1kw Crown Microtech, BBE 383 bass preamp and a
    pair of Fender bass cabinets stacked. 1 4x10 and 1 1x18. Back when I was
    gigging we used 4 Wharfdale 2800's for the front sound. Two bridged for
    the 4x18 folded horns at 3000 mono per side. The other two powered 4
    Community 3 ways at 4 ohms. That's 6000 + 5600 or 11,600 watts into 4
    ohms. Our drum kit was miked x 8 with two overheads. Everything else
    either miked or direct into a Mackie Onyx 32.4. Side fills and monitors
    were separate and ran by me on stage off a pair of rackmount Onyx 16's
    and a pair of older Panasonic Ramsa 300 watt amps.

    We weren't a particularly loud band but had the gear to be very clear and
    punchy with lots of reserve power.


    --
    Live Fast, Die Young and Leave a Pretty Corpse
     
    Meat Plow, Aug 26, 2010
    #10
  11. Meat Plow Guest

    On Thu, 26 Aug 2010 19:01:15 +0100, ian field wrote:

    > "Desk Rabbit" <> wrote in message
    > news:i568q4$3ct$...
    >> On 26/08/2010 17:51, ian field wrote:
    >>> "Desk Rabbit"<> wrote in message
    >>> news:i564ks$klr$...
    >>>> On 26/08/2010 17:01, wrote:
    >>>>> This may be a dumb question but do USB powered laptop speaker not
    >>>>> only get their power via the USB connection but the sound SIGNAL as
    >>>>> well?
    >>>> I doubt there's much power in the signal (which will be a digital
    >>>> stream anyway) but there is a 5volt power available from the USB port
    >>>> which should be enough to power a small amplifier.
    >>>
    >>> A BTL amplifier can produce pretty impressive output for only 5V
    >>> supply.

    >>
    >> I'm sure it can but bear in mind that most USB ports can only deliver
    >> 5v @ 500ma which is not a lot to play with. Your values of impressive
    >> must be considerably lower than mine - I do get to play with 3Kw+ PA
    >> systems occasionally though, now that is an impressive output ;-)
    >>
    >>

    > Did you somehow miss the bit where I said "for a 5V supply"?


    That's Desk Rabbit, he never misses a thing.



    --
    Live Fast, Die Young and Leave a Pretty Corpse
     
    Meat Plow, Aug 26, 2010
    #11
  12. VanguardLH Guest

    Desk Rabbit wrote:

    > me (needs a better moniker) wrote:
    >
    >> This may be a dumb question but do USB powered laptop
    >> speaker not only get their power via the USB connection
    >> but the sound SIGNAL as well?

    >
    > I doubt there's much power in the signal (which will be a digital stream
    > anyway) but there is a 5volt power available from the USB port which
    > should be enough to power a small amplifier.


    Just half an amp (across the *pair* of USB ports; i.e., the current from
    the controller for both of the paired ports connected to it) is all you
    get. The current load is shared by both ports. So you won't get much
    ooomph out of those speakers if all they use is the USB port for power
    (2.5W but then no device has 100% efficiency so the speakers will put
    out much less than that). If you suck up all the current in a
    high-power USB device, you cannot use the other paired port. There are
    some high-powered USB devices that will cause improper operation of a
    device plugged into the other paired USB port. 2W *out* is actually a
    lot of power (noise) but you won't get anywhere near 2W out when putting
    2W into a speaker unit. Although there might be 2.5W available from the
    USB controller, that doesn't mean you get that at the input to the
    speaker itself. Some of it gets consumed for the conversion logic
    inside the self-powered speakers (speakers are analog devices).

    http://stereos.about.com/od/stereoscience/a/amppower.htm
    http://everything2.com/title/Speaker efficiency

    USB-connected speakers will get their digital data stream from the USB
    ports. If they are weak but portable speakers then they may not have
    their own power supply. Because they are inefficient speakers with no
    amplification for the peaks in the sound, you get a very limited range
    reproduced by the speakers. For recognizable voice reproduction, they'd
    be okay. For typical external speakers, they are *powered* speakers
    (not self-powered or USB-powered) which means they have their own power
    supply and which means you have to plug in their power cord.

    For headsets (or unpowered external speakers with crappy output), the
    USB port can be the power source. For most external speakers, no matter
    from where they get their audio input, they usually have their own power
    supply (inside them or a brick in their power cord).

    If the OP is thinking of portability (not having to plug in a power
    cord), I'd suggest getting a USB headset to have some decent sound
    reproduction.
     
    VanguardLH, Aug 26, 2010
    #12
  13. VanguardLH Guest

    ian field wrote:

    > "Desk Rabbit" <> wrote in message
    > news:i568q4$3ct$...
    >> On 26/08/2010 17:51, ian field wrote:
    >>> "Desk Rabbit"<> wrote in message
    >>> news:i564ks$klr$...
    >>>> On 26/08/2010 17:01, wrote:
    >>>>> This may be a dumb question but do USB powered laptop
    >>>>> speaker not only get their power via the USB connection
    >>>>> but the sound SIGNAL as well?
    >>>> I doubt there's much power in the signal (which will be a digital stream
    >>>> anyway) but there is a 5volt power available from the USB port which
    >>>> should be enough to power a small amplifier.
    >>>
    >>> A BTL amplifier can produce pretty impressive output for only 5V supply.

    >>
    >> I'm sure it can but bear in mind that most USB ports can only deliver 5v @
    >> 500ma which is not a lot to play with. Your values of impressive must be
    >> considerably lower than mine - I do get to play with 3Kw+ PA systems
    >> occasionally though, now that is an impressive output ;-)
    >>

    >
    > Did you somehow miss the bit where I said "for a 5V supply"?


    Did you somehow miss that you only get a max of 1/2 amp (from the USB
    controller which means it is shared for the paired USB ports)? Just how
    do YOU compute the maximum amount of power given voltage and current?
    And, of course, a digital signal never needs logic for conversion to
    analog for speakers, huh? Just what do you think the speakers would
    sound like if a digital signal were applied directly to them? And just
    where did you find those 100% efficient power supplies, 100% efficient
    converters, and 100% speakers?

    A differential amplifier isn't going to overcome having a lower power
    source. You thought laptop speakers were great sounding? We don't know
    what the OP might have in mind. Lower input power to, say, a headset is
    sufficient for good sound reproduction but not if you talking about some
    crappy inefficient speakers in a case that have to compete with ambient
    noise and are not directly over the listener's ears.

    You see boobs misleading consumers with specs like this:

    http://www.usbgear.com/computer_cable_details.cfm?sku=B-59&cats=164&catid=121,136,164

    Oh yeah, you're gonna get 30W out or 4W RMS (from the speakers measure 1
    meter away) with only a 2.5W power source. Uh huh. Oh yeah, they have
    a huge capacitor to act as battery or a rechargeable batter that charges
    during long periods of non-use to fuel the amp inside so the speaker can
    produce far greater power output for short periods than is available
    from the power source itself, sure, that must be it, uh huh.

    There are USB-attached devices that will charge from the USB port but
    obviously all they're going to get out of the USB controller is 2.5W
    maximum. You certainly can't be doing a long charging cycle while also
    producing 30W output from a speaker (with far greater power consumption
    on the input side). There are even USB-powered battery chargers but you
    don't *use* the batteries while charging.
     
    VanguardLH, Aug 26, 2010
    #13
  14. ian field Guest

    "VanguardLH" <> wrote in message
    news:i56dep$ure$...
    > ian field wrote:
    >
    >> "Desk Rabbit" <> wrote in message
    >> news:i568q4$3ct$...
    >>> On 26/08/2010 17:51, ian field wrote:
    >>>> "Desk Rabbit"<> wrote in message
    >>>> news:i564ks$klr$...
    >>>>> On 26/08/2010 17:01, wrote:
    >>>>>> This may be a dumb question but do USB powered laptop
    >>>>>> speaker not only get their power via the USB connection
    >>>>>> but the sound SIGNAL as well?
    >>>>> I doubt there's much power in the signal (which will be a digital
    >>>>> stream
    >>>>> anyway) but there is a 5volt power available from the USB port which
    >>>>> should be enough to power a small amplifier.
    >>>>
    >>>> A BTL amplifier can produce pretty impressive output for only 5V
    >>>> supply.
    >>>
    >>> I'm sure it can but bear in mind that most USB ports can only deliver 5v
    >>> @
    >>> 500ma which is not a lot to play with. Your values of impressive must be
    >>> considerably lower than mine - I do get to play with 3Kw+ PA systems
    >>> occasionally though, now that is an impressive output ;-)
    >>>

    >>
    >> Did you somehow miss the bit where I said "for a 5V supply"?

    >
    > Did you somehow miss that you only get a max of 1/2 amp (from the USB
    > controller which means it is shared for the paired USB ports)? Just how
    > do YOU compute the maximum amount of power given voltage and current?
    > And, of course, a digital signal never needs logic for conversion to
    > analog for speakers, huh? Just what do you think the speakers would
    > sound like if a digital signal were applied directly to them?


    Are you on drugs?
     
    ian field, Aug 26, 2010
    #14
  15. ian field Guest

    "VanguardLH" <> wrote in message
    news:i56c4l$srs$...
    > Desk Rabbit wrote:
    >
    >> me (needs a better moniker) wrote:
    >>
    >>> This may be a dumb question but do USB powered laptop
    >>> speaker not only get their power via the USB connection
    >>> but the sound SIGNAL as well?

    >>
    >> I doubt there's much power in the signal (which will be a digital stream
    >> anyway) but there is a 5volt power available from the USB port which
    >> should be enough to power a small amplifier.

    >
    > Just half an amp (across the *pair* of USB ports; i.e., the current from
    > the controller for both of the paired ports connected to it) is all you
    > get. The current load is shared by both ports. So you won't get much
    > ooomph out of those speakers if all they use is the USB port for power
    > (2.5W but then no device has 100% efficiency so the speakers will put
    > out much less than that). If you suck up all the current in a
    > high-power USB device, you cannot use the other paired port. There are
    > some high-powered USB devices that will cause improper operation of a
    > device plugged into the other paired USB port. 2W *out* is actually a
    > lot of power (noise) but you won't get anywhere near 2W out when putting
    > 2W into a speaker unit. Although there might be 2.5W available from the
    > USB controller, that doesn't mean you get that at the input to the
    > speaker itself. Some of it gets consumed for the conversion logic
    > inside the self-powered speakers (speakers are analog devices).
    >
    > http://stereos.about.com/od/stereoscience/a/amppower.htm
    > http://everything2.com/title/Speaker efficiency
    >
    > USB-connected speakers will get their digital data stream from the USB
    > ports. If they are weak but portable speakers then they may not have
    > their own power supply. Because they are inefficient speakers with no
    > amplification for the peaks in the sound, you get a very limited range
    > reproduced by the speakers. For recognizable voice reproduction, they'd
    > be okay. For typical external speakers, they are *powered* speakers
    > (not self-powered or USB-powered) which means they have their own power
    > supply and which means you have to plug in their power cord.
    >
    > For headsets (or unpowered external speakers with crappy output), the
    > USB port can be the power source. For most external speakers, no matter
    > from where they get their audio input, they usually have their own power
    > supply (inside them or a brick in their power cord).
    >
    > If the OP is thinking of portability (not having to plug in a power
    > cord), I'd suggest getting a USB headset to have some decent sound
    > reproduction.
    >


    You seem to be assuming the OP wants to output a continuous sinewave at
    2.5W - you're more of a fuckwit than I already gave you credit for.

    A decent electro in the unit would cater for all but the loudest peaks and
    modern CMOS ASICs are such low power you could run them on a so called "eco
    battery" - 2 dissimilar metals stuck in a lemon.
     
    ian field, Aug 26, 2010
    #15
  16. ian field Guest

    "VanguardLH" <> wrote in message
    news:i56c4l$srs$...
    > Desk Rabbit wrote:
    >
    >> me (needs a better moniker) wrote:
    >>
    >>> This may be a dumb question but do USB powered laptop
    >>> speaker not only get their power via the USB connection
    >>> but the sound SIGNAL as well?

    >>
    >> I doubt there's much power in the signal (which will be a digital stream
    >> anyway) but there is a 5volt power available from the USB port which
    >> should be enough to power a small amplifier.

    >
    > Just half an amp (across the *pair* of USB ports; i.e., the current from
    > the controller for both of the paired ports connected to it) is all you
    > get. The current load is shared by both ports. So you won't get much
    > ooomph out of those speakers if all they use is the USB port for power
    > (2.5W but then no device has 100% efficiency so the speakers will put
    > out much less than that). If you suck up all the current in a
    > high-power USB device, you cannot use the other paired port. There are
    > some high-powered USB devices that will cause improper operation of a
    > device plugged into the other paired USB port. 2W *out* is actually a
    > lot of power (noise) but you won't get anywhere near 2W out when putting
    > 2W into a speaker unit. Although there might be 2.5W available from the
    > USB controller, that doesn't mean you get that at the input to the
    > speaker itself. Some of it gets consumed for the conversion logic
    > inside the self-powered speakers (speakers are analog devices).
    >
    > http://stereos.about.com/od/stereoscience/a/amppower.htm
    > http://everything2.com/title/Speaker efficiency
    >
    > USB-connected speakers will get their digital data stream from the USB
    > ports. If they are weak but portable speakers then they may not have
    > their own power supply. Because they are inefficient speakers with no
    > amplification for the peaks in the sound, you get a very limited range
    > reproduced by the speakers. For recognizable voice reproduction, they'd
    > be okay. For typical external speakers, they are *powered* speakers
    > (not self-powered or USB-powered) which means they have their own power
    > supply and which means you have to plug in their power cord.
    >
    > For headsets (or unpowered external speakers with crappy output), the
    > USB port can be the power source. For most external speakers, no matter
    > from where they get their audio input, they usually have their own power
    > supply (inside them or a brick in their power cord).
    >
    > If the OP is thinking of portability (not having to plug in a power
    > cord), I'd suggest getting a USB headset to have some decent sound
    > reproduction.
    >


    You seem to be assuming the OP wants to output a continuous sinewave at
    2.5W - you're more of a fuckwit than I already gave you credit for.

    A decent electro in the unit would cater for all but the loudest peaks and
    modern CMOS ASICs are such low power you could run them on a so called "eco
    battery" - 2 dissimilar metals stuck in a lemon.
     
    ian field, Aug 26, 2010
    #16
  17. VanguardLH Guest

    ian field wrote:

    > "VanguardLH" <> wrote in message
    > news:i56dep$ure$...
    >> ian field wrote:
    >>
    >>> "Desk Rabbit" <> wrote in message
    >>> news:i568q4$3ct$...
    >>>> On 26/08/2010 17:51, ian field wrote:
    >>>>> "Desk Rabbit"<> wrote in message
    >>>>> news:i564ks$klr$...
    >>>>>> On 26/08/2010 17:01, wrote:
    >>>>>>> This may be a dumb question but do USB powered laptop
    >>>>>>> speaker not only get their power via the USB connection
    >>>>>>> but the sound SIGNAL as well?
    >>>>>> I doubt there's much power in the signal (which will be a digital
    >>>>>> stream
    >>>>>> anyway) but there is a 5volt power available from the USB port which
    >>>>>> should be enough to power a small amplifier.
    >>>>>
    >>>>> A BTL amplifier can produce pretty impressive output for only 5V
    >>>>> supply.
    >>>>
    >>>> I'm sure it can but bear in mind that most USB ports can only deliver 5v
    >>>> @
    >>>> 500ma which is not a lot to play with. Your values of impressive must be
    >>>> considerably lower than mine - I do get to play with 3Kw+ PA systems
    >>>> occasionally though, now that is an impressive output ;-)
    >>>>
    >>>
    >>> Did you somehow miss the bit where I said "for a 5V supply"?

    >>
    >> Did you somehow miss that you only get a max of 1/2 amp (from the USB
    >> controller which means it is shared for the paired USB ports)? Just how
    >> do YOU compute the maximum amount of power given voltage and current?
    >> And, of course, a digital signal never needs logic for conversion to
    >> analog for speakers, huh? Just what do you think the speakers would
    >> sound like if a digital signal were applied directly to them?

    >
    > Are you on drugs?


    It's obvious that you have never heard USB-powered speakers.
     
    VanguardLH, Aug 26, 2010
    #17
  18. Meat Plow Guest

    On Thu, 26 Aug 2010 20:25:57 +0100, ian field wrote:

    > "VanguardLH" <> wrote in message
    > news:i56c4l$srs$...
    >> Desk Rabbit wrote:
    >>
    >>> me (needs a better moniker) wrote:
    >>>
    >>>> This may be a dumb question but do USB powered laptop speaker not
    >>>> only get their power via the USB connection but the sound SIGNAL as
    >>>> well?
    >>>
    >>> I doubt there's much power in the signal (which will be a digital
    >>> stream anyway) but there is a 5volt power available from the USB port
    >>> which should be enough to power a small amplifier.

    >>
    >> Just half an amp (across the *pair* of USB ports; i.e., the current
    >> from the controller for both of the paired ports connected to it) is
    >> all you get. The current load is shared by both ports. So you won't
    >> get much ooomph out of those speakers if all they use is the USB port
    >> for power (2.5W but then no device has 100% efficiency so the speakers
    >> will put out much less than that). If you suck up all the current in a
    >> high-power USB device, you cannot use the other paired port. There are
    >> some high-powered USB devices that will cause improper operation of a
    >> device plugged into the other paired USB port. 2W *out* is actually a
    >> lot of power (noise) but you won't get anywhere near 2W out when
    >> putting 2W into a speaker unit. Although there might be 2.5W available
    >> from the USB controller, that doesn't mean you get that at the input to
    >> the speaker itself. Some of it gets consumed for the conversion logic
    >> inside the self-powered speakers (speakers are analog devices).
    >>
    >> http://stereos.about.com/od/stereoscience/a/amppower.htm
    >> http://everything2.com/title/Speaker efficiency
    >>
    >> USB-connected speakers will get their digital data stream from the USB
    >> ports. If they are weak but portable speakers then they may not have
    >> their own power supply. Because they are inefficient speakers with no
    >> amplification for the peaks in the sound, you get a very limited range
    >> reproduced by the speakers. For recognizable voice reproduction,
    >> they'd be okay. For typical external speakers, they are *powered*
    >> speakers (not self-powered or USB-powered) which means they have their
    >> own power supply and which means you have to plug in their power cord.
    >>
    >> For headsets (or unpowered external speakers with crappy output), the
    >> USB port can be the power source. For most external speakers, no
    >> matter from where they get their audio input, they usually have their
    >> own power supply (inside them or a brick in their power cord).
    >>
    >> If the OP is thinking of portability (not having to plug in a power
    >> cord), I'd suggest getting a USB headset to have some decent sound
    >> reproduction.
    >>
    >>

    > You seem to be assuming the OP wants to output a continuous sinewave at
    > 2.5W - you're more of a fuckwit than I already gave you credit for.
    >
    > A decent electro in the unit would cater for all but the loudest peaks
    > and modern CMOS ASICs are such low power you could run them on a so
    > called "eco battery" - 2 dissimilar metals stuck in a lemon.


    I own a TINY IPod Shuffle. Granted I use a pair of IPod in-ear phones
    however it is so loud and has such dynamic sound I nearly pissed myself
    the first time I heard it. It runs off 5 volts, well let's just say it
    charges off the USB port. Also have a couple single cell Mini Disc
    players that run off a single 2000mah NiMH. Here again used with the
    Apple phones but at what, 3 volts (1.2v to 3v inverter/multivibrator)
    they have incredible sound, especially the Sharp SR60 MD.

    So at 5 volts you can get very loud and decent sound from today's
    electronics.



    --
    Live Fast, Die Young and Leave a Pretty Corpse
     
    Meat Plow, Aug 26, 2010
    #18
  19. ian field Guest

    "VanguardLH" <> wrote in message
    news:i56gf8$3oq$...
    > ian field wrote:
    >
    >> "VanguardLH" <> wrote in message
    >> news:i56dep$ure$...
    >>> ian field wrote:
    >>>
    >>>> "Desk Rabbit" <> wrote in message
    >>>> news:i568q4$3ct$...
    >>>>> On 26/08/2010 17:51, ian field wrote:
    >>>>>> "Desk Rabbit"<> wrote in message
    >>>>>> news:i564ks$klr$...
    >>>>>>> On 26/08/2010 17:01, wrote:
    >>>>>>>> This may be a dumb question but do USB powered laptop
    >>>>>>>> speaker not only get their power via the USB connection
    >>>>>>>> but the sound SIGNAL as well?
    >>>>>>> I doubt there's much power in the signal (which will be a digital
    >>>>>>> stream
    >>>>>>> anyway) but there is a 5volt power available from the USB port which
    >>>>>>> should be enough to power a small amplifier.
    >>>>>>
    >>>>>> A BTL amplifier can produce pretty impressive output for only 5V
    >>>>>> supply.
    >>>>>
    >>>>> I'm sure it can but bear in mind that most USB ports can only deliver
    >>>>> 5v
    >>>>> @
    >>>>> 500ma which is not a lot to play with. Your values of impressive must
    >>>>> be
    >>>>> considerably lower than mine - I do get to play with 3Kw+ PA systems
    >>>>> occasionally though, now that is an impressive output ;-)
    >>>>>
    >>>>
    >>>> Did you somehow miss the bit where I said "for a 5V supply"?
    >>>
    >>> Did you somehow miss that you only get a max of 1/2 amp (from the USB
    >>> controller which means it is shared for the paired USB ports)? Just how
    >>> do YOU compute the maximum amount of power given voltage and current?
    >>> And, of course, a digital signal never needs logic for conversion to
    >>> analog for speakers, huh? Just what do you think the speakers would
    >>> sound like if a digital signal were applied directly to them?

    >>
    >> Are you on drugs?

    >
    > It's obvious that you have never heard USB-powered speakers.
    >


    Fuckwit.
     
    ian field, Aug 26, 2010
    #19
  20. ian field Guest

    "Meat Plow" <> wrote in message
    news:p...
    > On Thu, 26 Aug 2010 20:25:57 +0100, ian field wrote:
    >
    >> "VanguardLH" <> wrote in message
    >> news:i56c4l$srs$...
    >>> Desk Rabbit wrote:
    >>>
    >>>> me (needs a better moniker) wrote:
    >>>>
    >>>>> This may be a dumb question but do USB powered laptop speaker not
    >>>>> only get their power via the USB connection but the sound SIGNAL as
    >>>>> well?
    >>>>
    >>>> I doubt there's much power in the signal (which will be a digital
    >>>> stream anyway) but there is a 5volt power available from the USB port
    >>>> which should be enough to power a small amplifier.
    >>>
    >>> Just half an amp (across the *pair* of USB ports; i.e., the current
    >>> from the controller for both of the paired ports connected to it) is
    >>> all you get. The current load is shared by both ports. So you won't
    >>> get much ooomph out of those speakers if all they use is the USB port
    >>> for power (2.5W but then no device has 100% efficiency so the speakers
    >>> will put out much less than that). If you suck up all the current in a
    >>> high-power USB device, you cannot use the other paired port. There are
    >>> some high-powered USB devices that will cause improper operation of a
    >>> device plugged into the other paired USB port. 2W *out* is actually a
    >>> lot of power (noise) but you won't get anywhere near 2W out when
    >>> putting 2W into a speaker unit. Although there might be 2.5W available
    >>> from the USB controller, that doesn't mean you get that at the input to
    >>> the speaker itself. Some of it gets consumed for the conversion logic
    >>> inside the self-powered speakers (speakers are analog devices).
    >>>
    >>> http://stereos.about.com/od/stereoscience/a/amppower.htm
    >>> http://everything2.com/title/Speaker efficiency
    >>>
    >>> USB-connected speakers will get their digital data stream from the USB
    >>> ports. If they are weak but portable speakers then they may not have
    >>> their own power supply. Because they are inefficient speakers with no
    >>> amplification for the peaks in the sound, you get a very limited range
    >>> reproduced by the speakers. For recognizable voice reproduction,
    >>> they'd be okay. For typical external speakers, they are *powered*
    >>> speakers (not self-powered or USB-powered) which means they have their
    >>> own power supply and which means you have to plug in their power cord.
    >>>
    >>> For headsets (or unpowered external speakers with crappy output), the
    >>> USB port can be the power source. For most external speakers, no
    >>> matter from where they get their audio input, they usually have their
    >>> own power supply (inside them or a brick in their power cord).
    >>>
    >>> If the OP is thinking of portability (not having to plug in a power
    >>> cord), I'd suggest getting a USB headset to have some decent sound
    >>> reproduction.
    >>>
    >>>

    >> You seem to be assuming the OP wants to output a continuous sinewave at
    >> 2.5W - you're more of a fuckwit than I already gave you credit for.
    >>
    >> A decent electro in the unit would cater for all but the loudest peaks
    >> and modern CMOS ASICs are such low power you could run them on a so
    >> called "eco battery" - 2 dissimilar metals stuck in a lemon.

    >
    > I own a TINY IPod Shuffle. Granted I use a pair of IPod in-ear phones
    > however it is so loud and has such dynamic sound I nearly pissed myself
    > the first time I heard it. It runs off 5 volts, well let's just say it
    > charges off the USB port. Also have a couple single cell Mini Disc
    > players that run off a single 2000mah NiMH. Here again used with the
    > Apple phones but at what, 3 volts (1.2v to 3v inverter/multivibrator)
    > they have incredible sound, especially the Sharp SR60 MD.
    >
    > So at 5 volts you can get very loud and decent sound from today's
    > electronics.



    When I lost one of the foam pads off my Senheisser headphones I bought a
    pair of Philips headphones with silicon rubber ear buds that seat into the
    ear, they were sold as "super bass" or somesuch - the difference was
    incredible.

    I was using them on a walkman clone running on NiCd cells so the voltage was
    down a bit - the phones could still be uncomfortably loud.
     
    ian field, Aug 26, 2010
    #20
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